Mileage drop after major crash.

Could be anything. What was the damage? Where was it? What was repaired and what was replaced?

The mileage drop could be the cold weather, it could be new tyres/tires bedding in, it could be the wheel alignment etc.

 

Are you saying that you're getting LESS than 40-MPG?

Depending on your driving style, that's a pretty big drop. I'm not a hypermiler, and I'm knocking down 55+.

Depending on what was hit, and what was replaced/repaired, I would look inder the car to see if they replaced all of the goofy plastic 'underspoilers'---or whatever you call them. Did they replace a wheel? If so you might be dragging a corner from unrepaired damage in something like a bearing assy, missaligned suspension component, etc.... Tires, if replaced by non-HRR types, and not properly inflated could also be part of the problem.
Too many possibilities without knowing what was bashed in.
A 9,000 repair bill indicates pretty extensive damage---even in a Prius, but I'd still expect to get a car back that functioned approximately like it did before the incident.

Since your car now has a sullied title history, you have a pretty big incentive to get to the bottom of what's not working properly, and continue to drive it---unless you're one of the fortunate few that can shrug off four figures in depreciation and drive whatever you want to.
If this is the case, go pick out another one, trade yours in and put the whole thing behind you.

Good Luck.
Let us know how it shakes out!!!

 

definitely agree with the tires and alignment issues. did they use OEM parts or after market. I would ask the body shop or look at your estimate you may be pulling around a little more metal.